Nikalna is leaving voluntarily, while Nikaalna is to remove by order or by force.

If you want success then you will have to get yourself out (Nikaalna) from bad habits.

I want to get out (Nikalna) of here.

Very Good question

Keep it up..

Nikalna - to get out / to exit byself or itself from somewhere

Wo 5 baje nikal gaya. - He went out at 5 o'clock.

Nikaalna - to take out someone/something from somewhere

Usne apne bag se ek chaku nikaala. - He pull/took out one knife from his bag.

I must say there are more than a couple of ways to use this word with different meanings - some times you use it draw a conclusion, evacuate, expel and many more.

Sharing a link to give you a clear picture -

<a href="https://en.bab.la/dictionary/hindi-english/%E0%A4%A8%E0%A4%BF%E0%A4%95%E0%A4%BE%E0%A4%B2%E0%A4%A8%E0%A4%BE" rel="noopener noreferrer" target="_blank">https://en.bab.la/dictionary/hindi-english/%E0%A4%A8%E0%A4%BF%E0%A4%95%E0%A4%BE%E0%A4%B2%E0%A4%A8%E0%A4%BE</a>;

Ronaldo was dropped from team.

(Ronaldo ko team say NIKAAL liya)

I am leaving this house.

(Ma is ghar say NIKAL raha hn